Our 3 Muchacho's The Trans-America Trail Adventure went really smooth, almost too smooth! After completing the TAT, I felt a little let down that we never got lost on the TAT, never got a flat, and never had an mechanical issues! But then I realized how many times we were at the mercy of the weather, how our riding skills would be tested (and improved), how we dealt with making decisions as a group, etc. etc..... yep don't worry... there is plenty of Adventure on the TAT!
GPS went a long way towards "smoothing" the ride, we traveled faster because we did not have to constantly refer to the roll charts, set trip-meters and use cumbersome paper maps. However, even with GPS, it helped to have one rider with roll charts because that person could take the lead at times, and provide detailed turn-by-turn information.

Transferring paper TAT maps to GPS started a couple of months before our departure by spending an hour or two at the computer every other evening. It was a learning experience, and my methodology changed as I got deeper into it. The hardware and software I used are listed as follows:

Garmin eTREX Vista HCX with 1 GB memory card

Garmin Mapsource

Garmin 2008 Topographical Maps

Google Maps

TAT Paper Maps

The roads you will travel on the TAT are marked with a highlighter pen on the paper maps and the trip meter mileages that correspond with the roll-charts are labeled in a box and arrow. I used the MapSource track drawing tool like I would a highlighter pen to draw a line on the roads in MapSource.

To start, I pick an easily defined starting point on the TAT paper maps, in our case I used the town of Oark, AR.
Next, open Garmin MapSource and find Oark, AR. and start drawing a track on top of the road that is the TAT.
Sometimes the county road name or number that is on the paper map may not be the same as what is in MapSource.
If there is a lot of doubt, open your web browser and use Google Maps to clear up any confusion.

Tracks can only be drawn in a straight line, so to change a track's direction, create a point and continue drawing.
A Garmin track can contain up to 500 points (not the same as a way-point) , and the GPS can store up to 20 tracks.
Try to choose logical beginning and ending points for each track that can be used in your track naming convention.
For example here you can see that I have 14 tracks that make up the portion of the TAT we are to ride.

Track 01_oark_447.90 means this track starts in the town of Oark, AR and ends at the mileage "447.90" on the TAT paper map.
Track 02_447.90_211.90 starts at mileage "447.90" and ends at "211.90" on the TAT paper map.
You can see that the mileage went down during this track, which indicates that the trip meter was set to zero at some point.
Having the mileage in the track name helps me find my place on the paper maps when I needed to continue drawing tracks.

Here is a comparison between the TAT paper map and the track drawn in MapSource

After a while of drawing tracks, I realized the way-points should contain more useful information.
Way-points with a flag mean a turn is approaching, and the name of the road is included in the label.

Please note that you must spend your track drawing points wisely.
A track can contain a maximum of 500 points so be sure to not run out of points before you complete the track.
This means when the road is very complex use more points to draw with and where the road is straighter use fewer points.

It's helpful to draw the tracks on the road or as close as possible, especially at intersections where a turn is to be made.
Accurate tracks pay off while riding and looking for a turn, especially on a road with many intersections.
There are times when it is not necessary to draw a really twisted track that uses a lot of points.
If you know you need to simply arrive at the end of a very twisty section, draw a straight line across the apexes and make a way-point at the end.

Be sure to create backups of your MapSource files so you can recover if your computer goes down.

Quality Assurance: When you complete a track take a moment , when your not tired, and compare it to the paper maps.
Look for places that you may have made a wrong turn, or it was not clear where a road was to be found.
Sometimes you have to play detective using all three tools, TAT paper maps, MapSource and Google Maps to determine
if the track you have drawn truly follows the TAT route.
Good luck, it is very rewarding work which gives you great familiarity with the route and makes the adventure more enjoyable and safer.

Very good explanation of how to set-up your gps for the TAT. I especially liked your naming convention for the waypoints. This should help a lot of people out.

Only thing I would add - I found a few instances where the blue lines on Sam's maps did not match the directions on the roll charts. I always assumed the roll chart directions were correct when they disagreed with the maps.